Fire proof treatment solution and fire retardant material therefrom

ABSTRACT

A fire proof treatment solution capable of resolving problems, such as low solubility leading to low concentration and hence low combustion inhibiting effect and water solubility leading to a disadvantage of eluviation, of boron compounds used as a constituent of flame retarding treatment solution. In particular, a fire proof treatment solution produced by adding phosphoric acid and a silane coupling agent to a weak acid or weak alkali aqueous metal salt solution containing a boron compound to thereby obtain a mixed aqueous solution and adding a plant extract composed mainly of a polyphenol compound to the mixed aqueous solution. This fire proof treatment solution can be widely applied to members composed mainly of cellulose, such as wood, paper and natural fibers. This fire proof treatment solution can increase the fixation of chemicals to thereby attain a high combustion inhibiting effect and can minimize the occurrence of eluviation.

TECHNICAL FIELD FIELD OF THE INVENTION

The present invention relates to a fire proof treatment solution, moreparticularly, a fire proof treatment solution whose main component is aboron compound for the purpose of use mainly in a easily flammablearticle, i.e., an article whose main component is a cellulose, such as atimber, paper, natural fiber and the like.

BACKGROUND ART

(Conventional Technology)

It has conventionally been accepted that timbers, papers and naturalfibers, which are naturally occurring organic materials, are readilyflammable.

Especially from the viewpoint of architecture, a readily flammablenature is subjected to a restriction by a law which limits the useextremely, and thus the use is poorly promoted in spite of a uniquefavorable property associated with a natural organic material.

On the other hand, the shortcomings mentioned above is beneficial fromthe viewpoint of a recycling, which is attributable to an ability ofbeing disposed by combustion without posing any public pollution.

Accordingly, various technologies for a fire retardant strategy of anatural organic material, i.e., flame retardant treatment technologies,have been developed.

Currently, a combustion inhibiting effect of a flame retardant treatmentcan be classified into two types, namely, a physical effect and achemical effect, the latter being expected to be achieved by a flameretardant treatment solution.

Such a flame retardant treatment solution is presented in various formssuch as a phosphorus compound, nitrogen compound, boron compound,halogen compound and the like.

Nevertheless, such a phosphorus compound, nitrogen compound or halogencompound produces a large amount of a toxic gas-containing fume uponcombustion, while a phosphoric acid may cause a problematicdeterioration or discoloration of the material.

On the other hand, a boron compound does not produce any toxic gasattributable to a pyrolytic product upon combustion, and causes arelatively slight deterioration or discoloration of the material.

In addition, it has a preserving and ant-repelling effect, and allowsits target material to be a high value-added material.

An agent whose main component is a boron compound exhibits a high heatformation-suppressing performance due to its dehydrating calcinationeffect.

The term dehydrating calcination effect means an ability of the agent toform an acid or base upon heating whereby dehydrating cellulose at a lowtemperature within a short period to yield water and carbon.

Thus, this combustion inhibiting effect consists of two effects, namely,a water evaporation-induced endothermic effect and a reduction of theexothermic rate due to the formation of a carbon residue whosecombustion rate is low.

PROBLEMS TO BE SOLVED BY THE INVENTION

However, the use of a boron compound as a flame retardant treatmentsolution poses the following two problems to be solved:

-   -   1) the solubility is low and the combustion inhibiting effect is        reduced at a low concentration; and,    -   2) an eluviation occurs due to the solubility in water.

The present invention is intended to solve these problems by providing afire retardant treatment solution having a high combustion inhibitingeffect while avoiding the eluviation as far as possible.

DISCLOSURE OF THE INVENTION

(Means for Solving the Problem)

the inventors made an effort under the background described above andfinally discovered that the solubility is improved in the presence of ametal salt, that a silane coupling agent allows for a film-formingbehavior, and that the eluviation can be suppressed by a polyphenolicsubstance, whereby accomplishing the invention.

Thus, the present invention is (1) a fire proof treatment solutionobtained by adding a phosphoric acid and a silane coupling agent to aweakly acidic or weakly alkaline metal salt aqueous solution containinga boron compound to form a mixed aqueous solution and adding to saidmixed aqueous solution a plant extract whose main component is apolyphenolic compound.

It is also (2) a fire retardant treatment solution wherein the weaklyacidic or weakly alkaline metal salt is contained in an amount of 1 to10% by weight based on the total weight of all components.

It is also (3) a fire retardant treatment solution wherein the boroncompound is contained in an amount of 50 to 95% by weight based on thetotal weight of all components.

It is also (4) a fire retardant treatment solution wherein thephosphoric acid is contained in an amount of 1 to 10% by weight based onthe total weight of all components.

It is also (5) a fire retardant treatment solution wherein the silanecoupling agent is contained in an amount of 0.1 to 5% by weight based onthe total weight of all components.

It is also (6) a fire retardant treatment solution wherein the plantextract whose main component is a polyphenolic compound is contained inan amount of 0.5 to 40% by weight based on the total weight of allcomponents.

It is also (7) a fire retardant material obtained by adding a fireretardant treatment solution described above to an article whose maincomponent is cellulose.

It is also (8) a fire retardant material obtained by impregnating atimber with a fire retardant treatment solution described above.

It is also (9) a fire retardant material obtained by impregnating apaper with a fire retardant treatment solution described above.

It is also (10) a fire retardant material obtained by impregnating afiber with a fire retardant treatment solution described above.

The present invention may also be a combination of two or more of (1) to(10) described above, as long as its purpose is attained.

ADVANTAGEOUS EFFECT OF THE INVENTION

According to a fire retardant treatment solution of the presentinvention, the fixation of an agent is improved to enhance thecombustion inhibiting effect while suppressing the eluviation as far aspossible.

As a result, a fire retardant timber can be provided.

Moreover, such a fire retardant treatment solution can widely be appliedto an article whose main component is cellulose, such as a timber,paper, natural fiber and the like.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph showing the results of a combustion test of a testarticle (K).

FIG. 2 is a graph showing the results of a combustion test of a testarticle (L).

FIG. 3 shows the results of a ¹³C-NMR spectroscopy.

BEST MODE FOR CARRYING OUT THE INVENTION

A fire retardant treatment solution of the present invention is obtainedby adding a phosphoric acid and a silane coupling agent to a weaklyacidic or weakly alkaline metal salt aqueous solution containing a boroncompound to form a mixed aqueous solution and adding to said mixedaqueous solution a plant extract whose main component is a polyphenoliccompound.

As a result, an impregnation of a material leads to an extremeimprovement in terms of a combustion inhibiting effect and an eluviationinhibiting effect.

A material to be impregnated or applied is mainly an article whose maincomponent is cellulose, such as a timber, paper, natural fiber and thelike.

(Combustion Inhibiting Effect)

Since a boron compound itself exhibits a low solubility as is wellknown, a solution of the boron compound at a high concentration isrequired for an efficient penetration into a material.

Accordingly, in the present invention, the solubility is improved by acatalytic effect of a weakly acidic or weakly alkaline metal salt.

Such a weakly acidic or weakly alkaline metal salt used here is sodiumfluoride, sodium phosphite, sodium sulfite, sodium borofluoride and thelike.

The weakly acidic or weakly alkaline metal salt content is 1 to 10% byweight based on the total weight of all components.

Content less than 1% leads to a difficulty in dissolution of the boroncompound, while that exceeding 10% is not efficient in terms of theproducibility.

The total weight of all components as used herein means the total weightof each component, which is a fire retardant treatment solution exceptfor water.

Since said boron compound, when used alone, undergoes a conversion intoa powder after drying, its crystallinity should be changed by using aphosphoric acid and a silane coupling agent, which serves to impart thedried material with a film-forming ability.

As a result, the amount of the agent fixed in the material is increased,and an improved fixation is achieved, whereby obtaining an improvedcombustion inhibiting effect.

As a silane coupling agent, a representative includes ethoxysilane,methoxysilane and the like, and the experimentation employs thosesupplied by Shin-Etsu Chemical Co., Ltd., such as, for the exampleproducts names of KBM-602, KBM-603, KBE-603, KBM-903, KBE-903, KBE-04,KBM-13, KBM-22, KBE-22, LBE-103, KPN-3504, KBM-3063, KBM-3103C and thelike.

The silane coupling agent content is 0.1 to 5% by weight based on thetotal weight of all components.

Content less than 0.1% leads to a difficulty in imparting a film-formingability, while that exceeding 5% leads to an increased viscosity of thesolution which results in a difficulty in treating a material.

(Eluviation Inhibiting Effect)

It is also required to inhibit the eluviation of an agent (fireretardant treatment solution) in a wet state.

In the present invention, the eluviation level of an agent is reduced byusing a polyphenolic substance which is a component of a bark extract.

The reasons why a polyphenolic compound is used are the intention toachieve a chemical reaction which makes a boron compound hardlywater-soluble after drying the material as a result of the adsorption ofthe boron compound by the polyphenolic compound.

Such a chemical reaction is supported by Example 3 described below.

A polyphenolic compound used may be purified tannin or tannin which is acomponent of a bark extract obtained for example by extracting a cedarbark with water for 24 hours.

The polyphenolic compound content is 0.5 to 40% based on the totalweight of all components.

Content less than 0.5% leads to a poor effect, while that exceeding 40%leads to a possibility rather of a reduction in the amount of a boroncompound fixed.

The incorporation of a polyphenolic compound tends to raise thetemperature at which the solid components in the agent are precipitated.

When applying such an agent to a material, two methods may be employed.

In the first method, after impregnation with a polyphenolic compoundfollowed by drying, the material is impregnated with a boron compound.

In the second method, a boron compound and a polyphenolic compound aremixed in a solution, whose temperature is raised and maintained within arange causing no precipitation, whereby effecting a fixation inside thematerial.

In the present invention, the latter is employed in view of the fixationefficiency.

The present invention is further described in the following Exampleswhich are not intended to restrict the invention, and variousmodifications can be made.

EXAMPLE 1

(I) Validation of Drug Fixation Rate Upon Drying Article

First, a metal salt aqueous solution containing a boron compound wascombined with a phosphoric acid and a silane coupling agent[methoxysilane (KBM-22)] to form an aqueous solution mixture.

To this aqueous solution mixture, a tannin, as a plant extract whosemain component is a polyphenolic compound, was incorporated to yield atreatment solution 1 (corresponding to a fire retardant treatmentsolution).

On the other hand, a treatment solution 2 was prepared similarly to thetreatment solution 1 except for adding no tannin.

The amount (% by weight) of each component in the treatment solution 1and the treatment solution 2 is indicated in Table 1 shown below.

In the treatment solution 1 shown in Table 1, a test article made from atimber (A, B, C, D, E) was immersed for 3 hours while heating andmaintaining at an elevated temperature, whereby effecting animpregnation.

After the impregnation followed by drying, the weight (weight beforeeluviation) and the water content were measured.

The test article used herein was a timber piece having the size of 20cm×12 cm×5 cm.

Subsequently, each test article (A, B, C, D, E) was allowed to stand forthree days under a highly humid condition whose dry bulb temperature was65° C. and whose relative humidity was 90%.

This condition employed the settings which allow the eluviation to occurreadily.

A complete drying was accomplished at a constant temperature of 105° C.,and the weight (post-eluviation post drying weight) was measured.

The eluviation levels of 5 test articles (A, B, C, D, E) are as shown inTable 2 shown below.

Then, a test article of a timber piece of 20 cm×12 cm×5 cm (F, G, H, I,J) was provided, and treated with the treatment solution 2 similarly tothe test articles described above (A, B, C, D, E), weighed and examinedfor the water content.

The eluviation levels of 5 test articles (F, G, H, I, J) are as shown inTable 3 shown below.

As evident from Tables 2 and 3, the eluviation level was reducedmarkedly when using the treatment solution 1 when compared with thetreatment solution 2.

Accordingly, the use of a polyphenolic compound allows a sufficientagent eluviation inhibiting effect to be exerted.

While the amount of the polyphenolic compound in the treatment solution1 was about 1% based on the entire treatment solution, it may beincreased for the purpose of further improving the agent eluviationinhibiting effect.

EXAMPLE 2

(II) Validation of Combustion Inhibiting Effect

First, a metal salt aqueous solution containing a boron compound wascombined with a phosphoric acid and a silane coupling agent[methoxysilane (KBM-22)] to form an aqueous solution mixture.

To this aqueous solution mixture, tannin, as a plant extract whose maincomponent is a polyphenolic compound, was incorporated to yield atreatment solution 3. prepared similarly to the treatment solution 3except for adding no silane coupling agent (KBM-22).

The blending ratio (% by weight) of each component in the treatmentsolution 3 and the treatment solution 4 is indicated in Table 4 shownbelow.

In this Example, a test article made from a timber was impregnated withthe treatment solution 3 shown in Table 4, and the test article (K) wasexamined using an ISO cone calorie meter.

After a similar impregnation with the treatment solution 4, the testarticle (L) was examined similarly.

FIG. 1 is a graph showing the results of a combustion test of the testarticle (K).

These results indicate superiority to the standard performance of a fireretardant material prescribed in Construction Standard Act.

FIG. 2 is a graph showing the results of a combustion test of the testarticle (L).

These results indicate compliance with the standard performance of aquasi-fire retardant material prescribed in Construction Standard Act,but not with the standard performance of a fire retardant material.

Thus, by incorporating a silane coupling agent in a certain amount, afire retardant material under Construction Standard Art can be realized.

EXAMPLE 3

A treatment solution similar to the treatment solution 1 shown in Table1 except for using a catechin instead of the tannin was provided.

This treatment solution was subjected to a ¹³C-NMR spectroscopy.

In this case, the catechin (polyphenolic compound) which is a precursorof tannin was used instead of the tannin because it can readily beanalyzed for a ¹³C-NMR spectrum.

FIG. 3 shows the results of a ¹³C-NMR spectroscopy.

Since the peak attributable to the catechin was reduced in this figure,the catechin was considered to interact with other components in thetreatment solution, whereby effecting a chemical change in the catechin.

Industrial Applicability, Utility

While the present invention relates to a fire proof treatment solution,and more particularly, it is employed mainly in a easily flammablearticle, i.e., an article whose main component is a cellulose, such as atimber, paper, natural fiber and the like, it can be applied also tointerior wall paper, furniture, clothing materials and the like, with asimilar effect being expected as long as no deviation from theprinciple. TABLE 1 Treatment solution 1 Treatment solution 2(Formulation 1) (%) (Formulation 2) (%) Water 80.00 80.00 Weakly acidic/0.80 0.80 Weakly alkaline metal salt Borax 10.60 11.64 Boric acid 6.806.80 Phosphoric acid 0.66 0.66 KBM-22 0.10 0.10 Tannin 1.04 0.00 Total100.0 100.0

TABLE 2 [Eluviation level (with tannin)] Post-eluviation Agent TestPre-eluviation Pre-eluviation post- Pre-eluviation post- eluviationAgent eluviation article Pre-eluviation water content drying weightagent level drying weight level level/Pre-eluviation number weight (%)(g) (g) (g) (g) (g) agent level A 744 7.20 694.03 347.23 564.94 129.090.37 B 732 6.70 686.04 344.04 563.92 122.11 0.35 C 743 7.50 691.16349.16 559.15 132.01 0.38 D 727 7.00 679.44 339.84 554.42 125.02 0.37 E740 7.70 687.09 349.89 556.55 130.55 0.37

TABLE 3 [Eluviation level (without tannin)] Test Pre- Pre-eluviationPre-eluviation post- Pre-eluviation Post-eluviation post- Agent Agenteluviation article eluviation water content drying weight agent leveldrying weight eluviation level level/Pre-eluviation number weight (%)(g) (g) (g) (g) (g) agent level F 767 7.60 712.83 373.23 559.57 153.260.41 G 755 7.90 699.72 354.12 552.78 146.94 0.41 H 741 7.40 689.94346.74 553.34 136.61 0.39 I 745 7.50 693.02 345.02 557.19 135.83 0.39 J761 7.40 708.57 371.37 561.18 147.38 0.40

TABLE 4 Treatment solution 3 Treatment solution 4 (Formulation 3) (%)(Formulation 4) (%) Water 80.00 80.00 Weakly acidic/ 0.80 0.80 Weaklyalkaline metal salt Borax 10.60 10.70 Boric acid 6.80 6.80 Phosphoricacid 0.66 0.66 KBM-22 0.10 0.00 Tannin 1.04 1.04 Total 100.0 100.0

1. A fire proof treatment solution obtained by adding a phosphoric acidand a silane coupling agent to a weakly acidic or weakly alkaline metalsalt aqueous solution containing a boron compound to form a mixedaqueous solution and adding to said mixed aqueous solution a plantextract whose main component is a polyphenolic compound.
 2. A fireretardant treatment solution according to claim 1 wherein the weaklyacidic or weakly alkaline metal salt is contained in an amount of 1 to10% by weight based on the total weight of all components.
 3. A fireretardant treatment solution according to claim 1 wherein the boroncompound is contained in an amount of 50 to 95% by weight based on thetotal weight of all components.
 4. A fire retardant treatment solutionaccording to claim 1 wherein the phosphoric acid is contained in anamount of 1 to 10% by weight based on the total weight of allcomponents.
 5. A fire retardant treatment solution according to claim 1wherein the silane coupling agent is contained in an amount of 0.1 to 5%by weight based on the total weight of all components.
 6. A fireretardant treatment solution according to claim 1 wherein the plantextract whose main component is a polyphenolic compound is contained inan amount of 0.5 to 40% by weight based on the total weight of allcomponents.
 7. A fire retardant material obtained by adding a fireretardant treatment solution according to claim 1 to an article whosemain component is a cellulose.
 8. A fire retardant material obtained byimpregnating a timber with a fire retardant treatment solution accordingto claim
 1. 9. A fire retardant material obtained by impregnating apaper with a fire retardant treatment solution according to claim
 1. 10.A fire retardant material obtained by impregnating a fiber with a fireretardant treatment solution according to claim 1.